Merge branch 'master' of ssh://bitbucket.org/czan/honours

1 files changed, 405 insertions, 0 deletions

diff --git a/clang/lib/StaticAnalyzer/Core/ExplodedGraph.cpp b/clang/lib/StaticAnalyzer/Core/ExplodedGraph.cpp
new file mode 100644
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--- /dev/null
+++ b/clang/lib/StaticAnalyzer/Core/ExplodedGraph.cpp
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+//=-- ExplodedGraph.cpp - Local, Path-Sens. "Exploded Graph" -*- C++ -*------=//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+//
+//  This file defines the template classes ExplodedNode and ExplodedGraph,
+//  which represent a path-sensitive, intra-procedural "exploded graph."
+//
+//===----------------------------------------------------------------------===//
+
+#include "clang/StaticAnalyzer/Core/PathSensitive/ExplodedGraph.h"
+#include "clang/StaticAnalyzer/Core/PathSensitive/ProgramState.h"
+#include "clang/AST/Stmt.h"
+#include "clang/AST/ParentMap.h"
+#include "llvm/ADT/DenseSet.h"
+#include "llvm/ADT/DenseMap.h"
+#include "llvm/ADT/SmallVector.h"
+#include <vector>
+
+using namespace clang;
+using namespace ento;
+
+//===----------------------------------------------------------------------===//
+// Node auditing.
+//===----------------------------------------------------------------------===//
+
+// An out of line virtual method to provide a home for the class vtable.
+ExplodedNode::Auditor::~Auditor() {}
+
+#ifndef NDEBUG
+static ExplodedNode::Auditor* NodeAuditor = 0;
+#endif
+
+void ExplodedNode::SetAuditor(ExplodedNode::Auditor* A) {
+#ifndef NDEBUG
+  NodeAuditor = A;
+#endif
+}
+
+//===----------------------------------------------------------------------===//
+// Cleanup.
+//===----------------------------------------------------------------------===//
+
+static const unsigned CounterTop = 1000;
+
+ExplodedGraph::ExplodedGraph()
+  : NumNodes(0), reclaimNodes(false), reclaimCounter(CounterTop) {}
+
+ExplodedGraph::~ExplodedGraph() {}
+
+//===----------------------------------------------------------------------===//
+// Node reclamation.
+//===----------------------------------------------------------------------===//
+
+bool ExplodedGraph::shouldCollect(const ExplodedNode *node) {
+  // Reclaimn all nodes that match *all* the following criteria:
+  //
+  // (1) 1 predecessor (that has one successor)
+  // (2) 1 successor (that has one predecessor)
+  // (3) The ProgramPoint is for a PostStmt.
+  // (4) There is no 'tag' for the ProgramPoint.
+  // (5) The 'store' is the same as the predecessor.
+  // (6) The 'GDM' is the same as the predecessor.
+  // (7) The LocationContext is the same as the predecessor.
+  // (8) The PostStmt is for a non-consumed Stmt or Expr.
+
+  // Conditions 1 and 2.
+  if (node->pred_size() != 1 || node->succ_size() != 1)
+    return false;
+
+  const ExplodedNode *pred = *(node->pred_begin());
+  if (pred->succ_size() != 1)
+    return false;
+  
+  const ExplodedNode *succ = *(node->succ_begin());
+  if (succ->pred_size() != 1)
+    return false;
+
+  // Condition 3.
+  ProgramPoint progPoint = node->getLocation();
+  if (!isa<PostStmt>(progPoint) ||
+      (isa<CallEnter>(progPoint) || isa<CallExit>(progPoint)))
+    return false;
+
+  // Condition 4.
+  PostStmt ps = cast<PostStmt>(progPoint);
+  if (ps.getTag())
+    return false;
+  
+  if (isa<BinaryOperator>(ps.getStmt()))
+    return false;
+
+  // Conditions 5, 6, and 7.
+  ProgramStateRef state = node->getState();
+  ProgramStateRef pred_state = pred->getState();    
+  if (state->store != pred_state->store || state->GDM != pred_state->GDM ||
+      progPoint.getLocationContext() != pred->getLocationContext())
+    return false;
+  
+  // Condition 8.
+  if (const Expr *Ex = dyn_cast<Expr>(ps.getStmt())) {
+    ParentMap &PM = progPoint.getLocationContext()->getParentMap();
+    if (!PM.isConsumedExpr(Ex))
+      return false;
+  }
+  
+  return true; 
+}
+
+void ExplodedGraph::collectNode(ExplodedNode *node) {
+  // Removing a node means:
+  // (a) changing the predecessors successor to the successor of this node
+  // (b) changing the successors predecessor to the predecessor of this node
+  // (c) Putting 'node' onto freeNodes.
+  assert(node->pred_size() == 1 || node->succ_size() == 1);
+  ExplodedNode *pred = *(node->pred_begin());
+  ExplodedNode *succ = *(node->succ_begin());
+  pred->replaceSuccessor(succ);
+  succ->replacePredecessor(pred);
+  FreeNodes.push_back(node);
+  Nodes.RemoveNode(node);
+  --NumNodes;
+  node->~ExplodedNode();  
+}
+
+void ExplodedGraph::reclaimRecentlyAllocatedNodes() {
+  if (ChangedNodes.empty())
+    return;
+
+  // Only periodically relcaim nodes so that we can build up a set of
+  // nodes that meet the reclamation criteria.  Freshly created nodes
+  // by definition have no successor, and thus cannot be reclaimed (see below).
+  assert(reclaimCounter > 0);
+  if (--reclaimCounter != 0)
+    return;
+  reclaimCounter = CounterTop;
+
+  for (NodeVector::iterator it = ChangedNodes.begin(), et = ChangedNodes.end();
+       it != et; ++it) {
+    ExplodedNode *node = *it;
+    if (shouldCollect(node))
+      collectNode(node);
+  }
+  ChangedNodes.clear();
+}
+
+//===----------------------------------------------------------------------===//
+// ExplodedNode.
+//===----------------------------------------------------------------------===//
+
+static inline BumpVector<ExplodedNode*>& getVector(void *P) {
+  return *reinterpret_cast<BumpVector<ExplodedNode*>*>(P);
+}
+
+void ExplodedNode::addPredecessor(ExplodedNode *V, ExplodedGraph &G) {
+  assert (!V->isSink());
+  Preds.addNode(V, G);
+  V->Succs.addNode(this, G);
+#ifndef NDEBUG
+  if (NodeAuditor) NodeAuditor->AddEdge(V, this);
+#endif
+}
+
+void ExplodedNode::NodeGroup::replaceNode(ExplodedNode *node) {
+  assert(getKind() == Size1);
+  P = reinterpret_cast<uintptr_t>(node);
+  assert(getKind() == Size1);
+}
+
+void ExplodedNode::NodeGroup::addNode(ExplodedNode *N, ExplodedGraph &G) {
+  assert((reinterpret_cast<uintptr_t>(N) & Mask) == 0x0);
+  assert(!getFlag());
+
+  if (getKind() == Size1) {
+    if (ExplodedNode *NOld = getNode()) {
+      BumpVectorContext &Ctx = G.getNodeAllocator();
+      BumpVector<ExplodedNode*> *V = 
+        G.getAllocator().Allocate<BumpVector<ExplodedNode*> >();
+      new (V) BumpVector<ExplodedNode*>(Ctx, 4);
+      
+      assert((reinterpret_cast<uintptr_t>(V) & Mask) == 0x0);
+      V->push_back(NOld, Ctx);
+      V->push_back(N, Ctx);
+      P = reinterpret_cast<uintptr_t>(V) | SizeOther;
+      assert(getPtr() == (void*) V);
+      assert(getKind() == SizeOther);
+    }
+    else {
+      P = reinterpret_cast<uintptr_t>(N);
+      assert(getKind() == Size1);
+    }
+  }
+  else {
+    assert(getKind() == SizeOther);
+    getVector(getPtr()).push_back(N, G.getNodeAllocator());
+  }
+}
+
+unsigned ExplodedNode::NodeGroup::size() const {
+  if (getFlag())
+    return 0;
+
+  if (getKind() == Size1)
+    return getNode() ? 1 : 0;
+  else
+    return getVector(getPtr()).size();
+}
+
+ExplodedNode **ExplodedNode::NodeGroup::begin() const {
+  if (getFlag())
+    return NULL;
+
+  if (getKind() == Size1)
+    return (ExplodedNode**) (getPtr() ? &P : NULL);
+  else
+    return const_cast<ExplodedNode**>(&*(getVector(getPtr()).begin()));
+}
+
+ExplodedNode** ExplodedNode::NodeGroup::end() const {
+  if (getFlag())
+    return NULL;
+
+  if (getKind() == Size1)
+    return (ExplodedNode**) (getPtr() ? &P+1 : NULL);
+  else {
+    // Dereferencing end() is undefined behaviour. The vector is not empty, so
+    // we can dereference the last elem and then add 1 to the result.
+    return const_cast<ExplodedNode**>(getVector(getPtr()).end());
+  }
+}
+
+ExplodedNode *ExplodedGraph::getNode(const ProgramPoint &L,
+                                     ProgramStateRef State,
+                                     bool IsSink,
+                                     bool* IsNew) {
+  // Profile 'State' to determine if we already have an existing node.
+  llvm::FoldingSetNodeID profile;
+  void *InsertPos = 0;
+
+  NodeTy::Profile(profile, L, State, IsSink);
+  NodeTy* V = Nodes.FindNodeOrInsertPos(profile, InsertPos);
+
+  if (!V) {
+    if (!FreeNodes.empty()) {
+      V = FreeNodes.back();
+      FreeNodes.pop_back();
+    }
+    else {
+      // Allocate a new node.
+      V = (NodeTy*) getAllocator().Allocate<NodeTy>();
+    }
+
+    new (V) NodeTy(L, State, IsSink);
+
+    if (reclaimNodes)
+      ChangedNodes.push_back(V);
+
+    // Insert the node into the node set and return it.
+    Nodes.InsertNode(V, InsertPos);
+    ++NumNodes;
+
+    if (IsNew) *IsNew = true;
+  }
+  else
+    if (IsNew) *IsNew = false;
+
+  return V;
+}
+
+std::pair<ExplodedGraph*, InterExplodedGraphMap*>
+ExplodedGraph::Trim(const NodeTy* const* NBeg, const NodeTy* const* NEnd,
+               llvm::DenseMap<const void*, const void*> *InverseMap) const {
+
+  if (NBeg == NEnd)
+    return std::make_pair((ExplodedGraph*) 0,
+                          (InterExplodedGraphMap*) 0);
+
+  assert (NBeg < NEnd);
+
+  OwningPtr<InterExplodedGraphMap> M(new InterExplodedGraphMap());
+
+  ExplodedGraph* G = TrimInternal(NBeg, NEnd, M.get(), InverseMap);
+
+  return std::make_pair(static_cast<ExplodedGraph*>(G), M.take());
+}
+
+ExplodedGraph*
+ExplodedGraph::TrimInternal(const ExplodedNode* const* BeginSources,
+                            const ExplodedNode* const* EndSources,
+                            InterExplodedGraphMap* M,
+                   llvm::DenseMap<const void*, const void*> *InverseMap) const {
+
+  typedef llvm::DenseSet<const ExplodedNode*> Pass1Ty;
+  Pass1Ty Pass1;
+
+  typedef llvm::DenseMap<const ExplodedNode*, ExplodedNode*> Pass2Ty;
+  Pass2Ty& Pass2 = M->M;
+
+  SmallVector<const ExplodedNode*, 10> WL1, WL2;
+
+  // ===- Pass 1 (reverse DFS) -===
+  for (const ExplodedNode* const* I = BeginSources; I != EndSources; ++I) {
+    assert(*I);
+    WL1.push_back(*I);
+  }
+
+  // Process the first worklist until it is empty.  Because it is a std::list
+  // it acts like a FIFO queue.
+  while (!WL1.empty()) {
+    const ExplodedNode *N = WL1.back();
+    WL1.pop_back();
+
+    // Have we already visited this node?  If so, continue to the next one.
+    if (Pass1.count(N))
+      continue;
+
+    // Otherwise, mark this node as visited.
+    Pass1.insert(N);
+
+    // If this is a root enqueue it to the second worklist.
+    if (N->Preds.empty()) {
+      WL2.push_back(N);
+      continue;
+    }
+
+    // Visit our predecessors and enqueue them.
+    for (ExplodedNode** I=N->Preds.begin(), **E=N->Preds.end(); I!=E; ++I)
+      WL1.push_back(*I);
+  }
+
+  // We didn't hit a root? Return with a null pointer for the new graph.
+  if (WL2.empty())
+    return 0;
+
+  // Create an empty graph.
+  ExplodedGraph* G = MakeEmptyGraph();
+
+  // ===- Pass 2 (forward DFS to construct the new graph) -===
+  while (!WL2.empty()) {
+    const ExplodedNode *N = WL2.back();
+    WL2.pop_back();
+
+    // Skip this node if we have already processed it.
+    if (Pass2.find(N) != Pass2.end())
+      continue;
+
+    // Create the corresponding node in the new graph and record the mapping
+    // from the old node to the new node.
+    ExplodedNode *NewN = G->getNode(N->getLocation(), N->State, N->isSink(), 0);
+    Pass2[N] = NewN;
+
+    // Also record the reverse mapping from the new node to the old node.
+    if (InverseMap) (*InverseMap)[NewN] = N;
+
+    // If this node is a root, designate it as such in the graph.
+    if (N->Preds.empty())
+      G->addRoot(NewN);
+
+    // In the case that some of the intended predecessors of NewN have already
+    // been created, we should hook them up as predecessors.
+
+    // Walk through the predecessors of 'N' and hook up their corresponding
+    // nodes in the new graph (if any) to the freshly created node.
+    for (ExplodedNode **I=N->Preds.begin(), **E=N->Preds.end(); I!=E; ++I) {
+      Pass2Ty::iterator PI = Pass2.find(*I);
+      if (PI == Pass2.end())
+        continue;
+
+      NewN->addPredecessor(PI->second, *G);
+    }
+
+    // In the case that some of the intended successors of NewN have already
+    // been created, we should hook them up as successors.  Otherwise, enqueue
+    // the new nodes from the original graph that should have nodes created
+    // in the new graph.
+    for (ExplodedNode **I=N->Succs.begin(), **E=N->Succs.end(); I!=E; ++I) {
+      Pass2Ty::iterator PI = Pass2.find(*I);
+      if (PI != Pass2.end()) {
+        PI->second->addPredecessor(NewN, *G);
+        continue;
+      }
+
+      // Enqueue nodes to the worklist that were marked during pass 1.
+      if (Pass1.count(*I))
+        WL2.push_back(*I);
+    }
+  }
+
+  return G;
+}
+
+void InterExplodedGraphMap::anchor() { }
+
+ExplodedNode*
+InterExplodedGraphMap::getMappedNode(const ExplodedNode *N) const {
+  llvm::DenseMap<const ExplodedNode*, ExplodedNode*>::const_iterator I =
+    M.find(N);
+
+  return I == M.end() ? 0 : I->second;
+}
+